It's a tuple of $x$ and $w$, same as the example from recitation #7. You can ignore the $\langle \ \rangle$ signs if you prefer in this case.
(In general, $\langle y \rangle$ means an encoding of $y$. If $y$ is a simple string then the encoding can be simply $y$. If $y$ is something more complex, like a TM or a graph, then $\langle y \rangle$ is some representation of $y$).